Obama should learn from history and consider Russian ambition at Yalta 69 years ago.

Sixty-nine years after the American president traveled to the Crimean peninsula to capitulate to a Russian strongman, Barack Obama’s weakness is pushing the United States to another generational conflict with Moscow.

In exchange for some phony promises of future, multilateral cooperation, Franklin Roosevelt in 1945 sated Joseph Stalin’s appetite to expand the population of subjugates under Moscow’s thumb. Eastern European innocents would pay for that mistake in the cold, dark shadow of totalitarianism for nearly half a century. And Americans paid for it with a multibillion-dollar cold war that strained our budgets, dragged our economy, and posed an ever-present threat to the national psyche.

Roosevelt’s failure was to believe a land-grabber could be coaxed, instead of confronted, into submission. Of Stalin, he said, “I think that if I give him everything that I possibly can and ask nothing from him in return, noblesse oblige, he won’t try to annex anything and will work for a world of democracy and peace.” Sound familiar? President Obama’s performance in the current Crimean crisis bears all the marks of that same naïveté.

Obama seems to believe or, at a minimum, to hold out hope that multilateral shame can make a tyrant blush. Roosevelt, similarly, conceded Russian domination of Eastern Europe in exchange for Stalin’s agreement to become a member of the United Nations, where, Roosevelt presumably thought, Stalin would sit around the international family table and play nice.

Since Russian troops began massing on the border of Crimea, and then surrounding Ukrainian military assets, President Obama has couched his response only in terms of what the United States is doing to consult its allies. This leader of the free world, when put under pressure that only his office can address, resorts to speaking about process instead of principle. And as is ever the case, this president confuses talking with doing, and consultation with commitment.

The president speaks of a “cost” that Putin will pay for misbehavior in Ukraine, but no doubt the Russian president hears only echoes of the “red line” that Obama failed to enforce in Syria when Bashar Assad used chemical weapons against his own people.

In Roosevelt’s case, Crimea was but the scene of the mistake. For Obama, it’s more than a venue. The sovereign state of Ukraine has been called the “crown jewel” of the now-independent former Soviet Republics. It was home to a large share of the USSR’s nuclear weaponry, missiles the Ukrainians freely relinquished in exchange for promises — from Russia, promises of peace, and from the U.S. and United Kingdom, promises of protection. These accords, the Budapest Memorandum, weren’t a formal treaty, but for a president who uses scarcely any tool but rhetoric, that distinction should matter little.

The nuclear club is constantly in a state of flux. Ostensibly, most aspirants to it seek nuclear weapons to check a rival. The Ukrainians gave up their arsenal despite Russia’s aggressive past, trusting the Western sheriffs’ assurances of protection. If we make that Ukrainian decision a mistake by reneging now, it’s difficult to see how we will talk any other nation out of its nukes in the future.

Putin barely disguises his ambition to reestablish a larger and ever-growing sphere of influence for Moscow — and he doesn’t disguise at all his disdain for the democratic governance and liberty that the people of Eastern Europe deserve. President Obama knows both of these things about his counterpart but is loath to act with certainty to check either.

For this American president, multilateralism is not a process but an end. Cooperation and consensus are his principles, not his tools. While President Reagan and both Presidents Bush accepted the American mission to be effective even at the expense of being liked, this president wants to be seen as cooperative even at the expense of being just.

That, more than his inexperience, is the heart of Obama’s repeated failure abroad. Some have suggested that Obama’s timidity is rooted in a bohemian worldview that abhors conflict. Others peg it, more charitably, to a mushy optimism about a new world order ushered in by technology that adds a measure of leveling to the international playing field. Whatever the motivation, his weakness will prove expensive for America; it always does.

This president is often praised for his intelligence. The events in Crimea should spur us to revisit that notion, or at least to mark the difference between wisdom and intelligence. While the president of Russia is using military force to invade neighboring countries, our president is reducing the size of our military and boasting about the record number of Americans on food stamps. Obama conveys weakness to our allies and our enemies, but wise presidents have always understood that American weakness leads to violence, American strength to stability.

We spent two generations overcoming the failure to contain Russian ambition at Yalta. Here’s hoping President Obama takes a longer look at that history before he repeats it.